Uniturbulence and Alfv\'en Wave Solar Model in MPI-AMRVAC

TL;DR

This paper extends the Alfvén Wave Solar Model by incorporating kink wave contributions, demonstrating that kink waves can sustain coronal conditions more effectively than Alfvén waves alone without artificial heating.

Contribution

It introduces a new physics module in MPI-AMRVAC that includes kink wave effects and compares their heating efficiency to Alfvén waves in solar atmosphere simulations.

Findings

Kink wave-driven models can sustain a stable solar atmosphere without artificial heating.

Kink waves provide higher heating rates than Alfvén waves at equal energy input.

Simulations show realistic coronal temperature and density profiles with kink wave heating.

Abstract

The coronal heating problem remains a fundamental challenge in solar physics. While AWSoM-type models (Alfv\'en Wave Solar Model) have proven highly successful in reproducing the large-scale structure of the solar corona, they inherently neglect contributions from additional wave modes that arise when the effects of transverse structuring is fully incorporated into the magnetohydrodynamic (MHD) equations. In this paper, we compare the roles of kink wave- and Alfv\'en wave-driven heating in sustaining a region of the solar atmosphere, using newly developed physics and radiative cooling modules within MPI-AMRVAC. We extend the existing MHD physics module in MPI-AMRVAC by incorporating additional Alfv\'en and kink wave energy contributions to the MHD equations. We examine their roles in heating the solar atmosphere and driving the solar wind. To validate our approach, we compare numerical results from Python-based simulations with those obtained using the UAWSoM module in MPI-AMRVAC. Furthermore, we assess the heating efficiency of kink waves relative to that of pure Alfv\'en waves through two parameter studies: (1) exploring how different Alfv\'en wave reflection rates impact the simulated atmosphere, and (2) varying the relative magnitudes of Alfv\'en and kink wave energy injections. Finally, we present results from a larger-scale domain, sustained entirely by kink wave-driven heating. Our results show that kink wave-driven (UAWSoM) models are able to sustain a stable atmosphere without requiring any artificial background heating terms, unlike traditional Alfv\'en-only models. We attribute this to the increased heating rate associated with kink waves compared with Alfv\'en waves, given the same energy injection. Kink waves can sustain a model plasma with temperature and density values representative of coronal conditions without resorting to ad hoc heating terms.